linux_kernel/drivers/s390/crypto/ap_bus.c

/*
 * Copyright IBM Corp. 2006, 2012
 * Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
 *	      Martin Schwidefsky <schwidefsky@de.ibm.com>
 *	      Ralph Wuerthner <rwuerthn@de.ibm.com>
 *	      Felix Beck <felix.beck@de.ibm.com>
 *	      Holger Dengler <hd@linux.vnet.ibm.com>
 *
 * Adjunct processor bus.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define KMSG_COMPONENT "ap"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kernel_stat.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/suspend.h>
#include <asm/reset.h>
#include <asm/airq.h>
#include <linux/atomic.h>
#include <asm/isc.h>
#include <linux/hrtimer.h>
#include <linux/ktime.h>
#include <asm/facility.h>
#include <linux/crypto.h>
#include <linux/mod_devicetable.h>
#include <linux/debugfs.h>

#include "ap_bus.h"
#include "ap_asm.h"
#include "ap_debug.h"

/*
 * Module parameters; note though this file itself isn't modular.
 */
int ap_domain_index = -1;	/* Adjunct Processor Domain Index */
static DEFINE_SPINLOCK(ap_domain_lock);
module_param_named(domain, ap_domain_index, int, S_IRUSR|S_IRGRP);
MODULE_PARM_DESC(domain, "domain index for ap devices");
EXPORT_SYMBOL(ap_domain_index);

static int ap_thread_flag = 0;
module_param_named(poll_thread, ap_thread_flag, int, S_IRUSR|S_IRGRP);
MODULE_PARM_DESC(poll_thread, "Turn on/off poll thread, default is 0 (off).");

static struct device *ap_root_device;

DEFINE_SPINLOCK(ap_list_lock);
LIST_HEAD(ap_card_list);

static struct ap_config_info *ap_configuration;
static bool initialised;

/*
 * AP bus related debug feature things.
 */
debug_info_t *ap_dbf_info;

/*
 * Workqueue timer for bus rescan.
 */
static struct timer_list ap_config_timer;
static int ap_config_time = AP_CONFIG_TIME;
static void ap_scan_bus(struct work_struct *);
static DECLARE_WORK(ap_scan_work, ap_scan_bus);

/*
 * Tasklet & timer for AP request polling and interrupts
 */
static void ap_tasklet_fn(unsigned long);
static DECLARE_TASKLET(ap_tasklet, ap_tasklet_fn, 0);
static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait);
static struct task_struct *ap_poll_kthread = NULL;
static DEFINE_MUTEX(ap_poll_thread_mutex);
static DEFINE_SPINLOCK(ap_poll_timer_lock);
static struct hrtimer ap_poll_timer;
/* In LPAR poll with 4kHz frequency. Poll every 250000 nanoseconds.
 * If z/VM change to 1500000 nanoseconds to adjust to z/VM polling.*/
static unsigned long long poll_timeout = 250000;

/* Suspend flag */
static int ap_suspend_flag;
/* Maximum domain id */
static int ap_max_domain_id;
/* Flag to check if domain was set through module parameter domain=. This is
 * important when supsend and resume is done in a z/VM environment where the
 * domain might change. */
static int user_set_domain = 0;
static struct bus_type ap_bus_type;

/* Adapter interrupt definitions */
static void ap_interrupt_handler(struct airq_struct *airq);

static int ap_airq_flag;

static struct airq_struct ap_airq = {
	.handler = ap_interrupt_handler,
	.isc = AP_ISC,
};

/**
 * ap_using_interrupts() - Returns non-zero if interrupt support is
 * available.
 */
static inline int ap_using_interrupts(void)
{
	return ap_airq_flag;
}

/**
 * ap_airq_ptr() - Get the address of the adapter interrupt indicator
 *
 * Returns the address of the local-summary-indicator of the adapter
 * interrupt handler for AP, or NULL if adapter interrupts are not
 * available.
 */
void *ap_airq_ptr(void)
{
	if (ap_using_interrupts())
		return ap_airq.lsi_ptr;
	return NULL;
}

/**
 * ap_interrupts_available(): Test if AP interrupts are available.
 *
 * Returns 1 if AP interrupts are available.
 */
static int ap_interrupts_available(void)
{
	return test_facility(65);
}

/**
 * ap_configuration_available(): Test if AP configuration
 * information is available.
 *
 * Returns 1 if AP configuration information is available.
 */
static int ap_configuration_available(void)
{
	return test_facility(12);
}

/**
 * ap_test_queue(): Test adjunct processor queue.
 * @qid: The AP queue number
 * @info: Pointer to queue descriptor
 *
 * Returns AP queue status structure.
 */
static inline struct ap_queue_status
ap_test_queue(ap_qid_t qid, unsigned long *info)
{
	if (test_facility(15))
		qid |= 1UL << 23;		/* set APFT T bit*/
	return ap_tapq(qid, info);
}

static inline int ap_query_configuration(void)
{
	if (!ap_configuration)
		return -EOPNOTSUPP;
	return ap_qci(ap_configuration);
}

/**
 * ap_init_configuration(): Allocate and query configuration array.
 */
static void ap_init_configuration(void)
{
	if (!ap_configuration_available())
		return;

	ap_configuration = kzalloc(sizeof(*ap_configuration), GFP_KERNEL);
	if (!ap_configuration)
		return;
	if (ap_query_configuration() != 0) {
		kfree(ap_configuration);
		ap_configuration = NULL;
		return;
	}
}

/*
 * ap_test_config(): helper function to extract the nrth bit
 *		     within the unsigned int array field.
 */
static inline int ap_test_config(unsigned int *field, unsigned int nr)
{
	return ap_test_bit((field + (nr >> 5)), (nr & 0x1f));
}

/*
 * ap_test_config_card_id(): Test, whether an AP card ID is configured.
 * @id AP card ID
 *
 * Returns 0 if the card is not configured
 *	   1 if the card is configured or
 *	     if the configuration information is not available
 */
static inline int ap_test_config_card_id(unsigned int id)
{
	if (!ap_configuration)	/* QCI not supported */
		return 1;
	return ap_test_config(ap_configuration->apm, id);
}

/*
 * ap_test_config_domain(): Test, whether an AP usage domain is configured.
 * @domain AP usage domain ID
 *
 * Returns 0 if the usage domain is not configured
 *	   1 if the usage domain is configured or
 *	     if the configuration information is not available
 */
static inline int ap_test_config_domain(unsigned int domain)
{
	if (!ap_configuration)	/* QCI not supported */
		return domain < 16;
	return ap_test_config(ap_configuration->aqm, domain);
}

/**
 * ap_query_queue(): Check if an AP queue is available.
 * @qid: The AP queue number
 * @queue_depth: Pointer to queue depth value
 * @device_type: Pointer to device type value
 * @facilities: Pointer to facility indicator
 */
static int ap_query_queue(ap_qid_t qid, int *queue_depth, int *device_type,
			  unsigned int *facilities)
{
	struct ap_queue_status status;
	unsigned long info;
	int nd;

	if (!ap_test_config_card_id(AP_QID_CARD(qid)))
		return -ENODEV;

	status = ap_test_queue(qid, &info);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		*queue_depth = (int)(info & 0xff);
		*device_type = (int)((info >> 24) & 0xff);
		*facilities = (unsigned int)(info >> 32);
		/* Update maximum domain id */
		nd = (info >> 16) & 0xff;
		/* if N bit is available, z13 and newer */
		if ((info & (1UL << 57)) && nd > 0)
			ap_max_domain_id = nd;
		else /* older machine types */
			ap_max_domain_id = 15;
		switch (*device_type) {
			/* For CEX2 and CEX3 the available functions
			 * are not refrected by the facilities bits.
			 * Instead it is coded into the type. So here
			 * modify the function bits based on the type.
			 */
		case AP_DEVICE_TYPE_CEX2A:
		case AP_DEVICE_TYPE_CEX3A:
			*facilities |= 0x08000000;
			break;
		case AP_DEVICE_TYPE_CEX2C:
		case AP_DEVICE_TYPE_CEX3C:
			*facilities |= 0x10000000;
			break;
		default:
			break;
		}
		return 0;
	case AP_RESPONSE_Q_NOT_AVAIL:
	case AP_RESPONSE_DECONFIGURED:
	case AP_RESPONSE_CHECKSTOPPED:
	case AP_RESPONSE_INVALID_ADDRESS:
		return -ENODEV;
	case AP_RESPONSE_RESET_IN_PROGRESS:
	case AP_RESPONSE_OTHERWISE_CHANGED:
	case AP_RESPONSE_BUSY:
		return -EBUSY;
	default:
		BUG();
	}
}

void ap_wait(enum ap_wait wait)
{
	ktime_t hr_time;

	switch (wait) {
	case AP_WAIT_AGAIN:
	case AP_WAIT_INTERRUPT:
		if (ap_using_interrupts())
			break;
		if (ap_poll_kthread) {
			wake_up(&ap_poll_wait);
			break;
		}
		/* Fall through */
	case AP_WAIT_TIMEOUT:
		spin_lock_bh(&ap_poll_timer_lock);
		if (!hrtimer_is_queued(&ap_poll_timer)) {
			hr_time = poll_timeout;
			hrtimer_forward_now(&ap_poll_timer, hr_time);
			hrtimer_restart(&ap_poll_timer);
		}
		spin_unlock_bh(&ap_poll_timer_lock);
		break;
	case AP_WAIT_NONE:
	default:
		break;
	}
}

/**
 * ap_request_timeout(): Handling of request timeouts
 * @data: Holds the AP device.
 *
 * Handles request timeouts.
 */
void ap_request_timeout(unsigned long data)
{
	struct ap_queue *aq = (struct ap_queue *) data;

	if (ap_suspend_flag)
		return;
	spin_lock_bh(&aq->lock);
	ap_wait(ap_sm_event(aq, AP_EVENT_TIMEOUT));
	spin_unlock_bh(&aq->lock);
}

/**
 * ap_poll_timeout(): AP receive polling for finished AP requests.
 * @unused: Unused pointer.
 *
 * Schedules the AP tasklet using a high resolution timer.
 */
static enum hrtimer_restart ap_poll_timeout(struct hrtimer *unused)
{
	if (!ap_suspend_flag)
		tasklet_schedule(&ap_tasklet);
	return HRTIMER_NORESTART;
}

/**
 * ap_interrupt_handler() - Schedule ap_tasklet on interrupt
 * @airq: pointer to adapter interrupt descriptor
 */
static void ap_interrupt_handler(struct airq_struct *airq)
{
	inc_irq_stat(IRQIO_APB);
	if (!ap_suspend_flag)
		tasklet_schedule(&ap_tasklet);
}

/**
 * ap_tasklet_fn(): Tasklet to poll all AP devices.
 * @dummy: Unused variable
 *
 * Poll all AP devices on the bus.
 */
static void ap_tasklet_fn(unsigned long dummy)
{
	struct ap_card *ac;
	struct ap_queue *aq;
	enum ap_wait wait = AP_WAIT_NONE;

	/* Reset the indicator if interrupts are used. Thus new interrupts can
	 * be received. Doing it in the beginning of the tasklet is therefor
	 * important that no requests on any AP get lost.
	 */
	if (ap_using_interrupts())
		xchg(ap_airq.lsi_ptr, 0);

	spin_lock_bh(&ap_list_lock);
	for_each_ap_card(ac) {
		for_each_ap_queue(aq, ac) {
			spin_lock_bh(&aq->lock);
			wait = min(wait, ap_sm_event_loop(aq, AP_EVENT_POLL));
			spin_unlock_bh(&aq->lock);
		}
	}
	spin_unlock_bh(&ap_list_lock);

	ap_wait(wait);
}

static int ap_pending_requests(void)
{
	struct ap_card *ac;
	struct ap_queue *aq;

	spin_lock_bh(&ap_list_lock);
	for_each_ap_card(ac) {
		for_each_ap_queue(aq, ac) {
			if (aq->queue_count == 0)
				continue;
			spin_unlock_bh(&ap_list_lock);
			return 1;
		}
	}
	spin_unlock_bh(&ap_list_lock);
	return 0;
}

/**
 * ap_poll_thread(): Thread that polls for finished requests.
 * @data: Unused pointer
 *
 * AP bus poll thread. The purpose of this thread is to poll for
 * finished requests in a loop if there is a "free" cpu - that is
 * a cpu that doesn't have anything better to do. The polling stops
 * as soon as there is another task or if all messages have been
 * delivered.
 */
static int ap_poll_thread(void *data)
{
	DECLARE_WAITQUEUE(wait, current);

	set_user_nice(current, MAX_NICE);
	set_freezable();
	while (!kthread_should_stop()) {
		add_wait_queue(&ap_poll_wait, &wait);
		set_current_state(TASK_INTERRUPTIBLE);
		if (ap_suspend_flag || !ap_pending_requests()) {
			schedule();
			try_to_freeze();
		}
		set_current_state(TASK_RUNNING);
		remove_wait_queue(&ap_poll_wait, &wait);
		if (need_resched()) {
			schedule();
			try_to_freeze();
			continue;
		}
		ap_tasklet_fn(0);
	}

	return 0;
}

static int ap_poll_thread_start(void)
{
	int rc;

	if (ap_using_interrupts() || ap_poll_kthread)
		return 0;
	mutex_lock(&ap_poll_thread_mutex);
	ap_poll_kthread = kthread_run(ap_poll_thread, NULL, "appoll");
	rc = PTR_RET(ap_poll_kthread);
	if (rc)
		ap_poll_kthread = NULL;
	mutex_unlock(&ap_poll_thread_mutex);
	return rc;
}

static void ap_poll_thread_stop(void)
{
	if (!ap_poll_kthread)
		return;
	mutex_lock(&ap_poll_thread_mutex);
	kthread_stop(ap_poll_kthread);
	ap_poll_kthread = NULL;
	mutex_unlock(&ap_poll_thread_mutex);
}

#define is_card_dev(x) ((x)->parent == ap_root_device)
#define is_queue_dev(x) ((x)->parent != ap_root_device)

/**
 * ap_bus_match()
 * @dev: Pointer to device
 * @drv: Pointer to device_driver
 *
 * AP bus driver registration/unregistration.
 */
static int ap_bus_match(struct device *dev, struct device_driver *drv)
{
	struct ap_driver *ap_drv = to_ap_drv(drv);
	struct ap_device_id *id;

	/*
	 * Compare device type of the device with the list of
	 * supported types of the device_driver.
	 */
	for (id = ap_drv->ids; id->match_flags; id++) {
		if (is_card_dev(dev) &&
		    id->match_flags & AP_DEVICE_ID_MATCH_CARD_TYPE &&
		    id->dev_type == to_ap_dev(dev)->device_type)
			return 1;
		if (is_queue_dev(dev) &&
		    id->match_flags & AP_DEVICE_ID_MATCH_QUEUE_TYPE &&
		    id->dev_type == to_ap_dev(dev)->device_type)
			return 1;
	}
	return 0;
}

/**
 * ap_uevent(): Uevent function for AP devices.
 * @dev: Pointer to device
 * @env: Pointer to kobj_uevent_env
 *
 * It sets up a single environment variable DEV_TYPE which contains the
 * hardware device type.
 */
static int ap_uevent (struct device *dev, struct kobj_uevent_env *env)
{
	struct ap_device *ap_dev = to_ap_dev(dev);
	int retval = 0;

	if (!ap_dev)
		return -ENODEV;

	/* Set up DEV_TYPE environment variable. */
	retval = add_uevent_var(env, "DEV_TYPE=%04X", ap_dev->device_type);
	if (retval)
		return retval;

	/* Add MODALIAS= */
	retval = add_uevent_var(env, "MODALIAS=ap:t%02X", ap_dev->device_type);

	return retval;
}

static int ap_dev_suspend(struct device *dev)
{
	struct ap_device *ap_dev = to_ap_dev(dev);

	if (ap_dev->drv && ap_dev->drv->suspend)
		ap_dev->drv->suspend(ap_dev);
	return 0;
}

static int ap_dev_resume(struct device *dev)
{
	struct ap_device *ap_dev = to_ap_dev(dev);

	if (ap_dev->drv && ap_dev->drv->resume)
		ap_dev->drv->resume(ap_dev);
	return 0;
}

static void ap_bus_suspend(void)
{
	AP_DBF(DBF_DEBUG, "ap_bus_suspend running\n");

	ap_suspend_flag = 1;
	/*
	 * Disable scanning for devices, thus we do not want to scan
	 * for them after removing.
	 */
	flush_work(&ap_scan_work);
	tasklet_disable(&ap_tasklet);
}

static int __ap_card_devices_unregister(struct device *dev, void *dummy)
{
	if (is_card_dev(dev))
		device_unregister(dev);
	return 0;
}

static int __ap_queue_devices_unregister(struct device *dev, void *dummy)
{
	if (is_queue_dev(dev))
		device_unregister(dev);
	return 0;
}

static int __ap_queue_devices_with_id_unregister(struct device *dev, void *data)
{
	if (is_queue_dev(dev) &&
	    AP_QID_CARD(to_ap_queue(dev)->qid) == (int)(long) data)
		device_unregister(dev);
	return 0;
}

static void ap_bus_resume(void)
{
	int rc;

	AP_DBF(DBF_DEBUG, "ap_bus_resume running\n");

	/* remove all queue devices */
	bus_for_each_dev(&ap_bus_type, NULL, NULL,
			 __ap_queue_devices_unregister);
	/* remove all card devices */
	bus_for_each_dev(&ap_bus_type, NULL, NULL,
			 __ap_card_devices_unregister);

	/* Reset thin interrupt setting */
	if (ap_interrupts_available() && !ap_using_interrupts()) {
		rc = register_adapter_interrupt(&ap_airq);
		ap_airq_flag = (rc == 0);
	}
	if (!ap_interrupts_available() && ap_using_interrupts()) {
		unregister_adapter_interrupt(&ap_airq);
		ap_airq_flag = 0;
	}
	/* Reset domain */
	if (!user_set_domain)
		ap_domain_index = -1;
	/* Get things going again */
	ap_suspend_flag = 0;
	if (ap_airq_flag)
		xchg(ap_airq.lsi_ptr, 0);
	tasklet_enable(&ap_tasklet);
	queue_work(system_long_wq, &ap_scan_work);
}

static int ap_power_event(struct notifier_block *this, unsigned long event,
			  void *ptr)
{
	switch (event) {
	case PM_HIBERNATION_PREPARE:
	case PM_SUSPEND_PREPARE:
		ap_bus_suspend();
		break;
	case PM_POST_HIBERNATION:
	case PM_POST_SUSPEND:
		ap_bus_resume();
		break;
	default:
		break;
	}
	return NOTIFY_DONE;
}
static struct notifier_block ap_power_notifier = {
	.notifier_call = ap_power_event,
};

static SIMPLE_DEV_PM_OPS(ap_bus_pm_ops, ap_dev_suspend, ap_dev_resume);

static struct bus_type ap_bus_type = {
	.name = "ap",
	.match = &ap_bus_match,
	.uevent = &ap_uevent,
	.pm = &ap_bus_pm_ops,
};

static int ap_device_probe(struct device *dev)
{
	struct ap_device *ap_dev = to_ap_dev(dev);
	struct ap_driver *ap_drv = to_ap_drv(dev->driver);
	int rc;

	ap_dev->drv = ap_drv;
	rc = ap_drv->probe ? ap_drv->probe(ap_dev) : -ENODEV;
	if (rc)
		ap_dev->drv = NULL;
	return rc;
}

static int ap_device_remove(struct device *dev)
{
	struct ap_device *ap_dev = to_ap_dev(dev);
	struct ap_driver *ap_drv = ap_dev->drv;

	spin_lock_bh(&ap_list_lock);
	if (is_card_dev(dev))
		list_del_init(&to_ap_card(dev)->list);
	else
		list_del_init(&to_ap_queue(dev)->list);
	spin_unlock_bh(&ap_list_lock);
	if (ap_drv->remove)
		ap_drv->remove(ap_dev);
	return 0;
}

int ap_driver_register(struct ap_driver *ap_drv, struct module *owner,
		       char *name)
{
	struct device_driver *drv = &ap_drv->driver;

	if (!initialised)
		return -ENODEV;

	drv->bus = &ap_bus_type;
	drv->probe = ap_device_probe;
	drv->remove = ap_device_remove;
	drv->owner = owner;
	drv->name = name;
	return driver_register(drv);
}
EXPORT_SYMBOL(ap_driver_register);

void ap_driver_unregister(struct ap_driver *ap_drv)
{
	driver_unregister(&ap_drv->driver);
}
EXPORT_SYMBOL(ap_driver_unregister);

void ap_bus_force_rescan(void)
{
	if (ap_suspend_flag)
		return;
	/* processing a asynchronous bus rescan */
	del_timer(&ap_config_timer);
	queue_work(system_long_wq, &ap_scan_work);
	flush_work(&ap_scan_work);
}
EXPORT_SYMBOL(ap_bus_force_rescan);

/*
 * AP bus attributes.
 */
static ssize_t ap_domain_show(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%d\n", ap_domain_index);
}

static ssize_t ap_domain_store(struct bus_type *bus,
			       const char *buf, size_t count)
{
	int domain;

	if (sscanf(buf, "%i\n", &domain) != 1 ||
	    domain < 0 || domain > ap_max_domain_id)
		return -EINVAL;
	spin_lock_bh(&ap_domain_lock);
	ap_domain_index = domain;
	spin_unlock_bh(&ap_domain_lock);

	AP_DBF(DBF_DEBUG, "store new default domain=%d\n", domain);

	return count;
}

static BUS_ATTR(ap_domain, 0644, ap_domain_show, ap_domain_store);

static ssize_t ap_control_domain_mask_show(struct bus_type *bus, char *buf)
{
	if (!ap_configuration)	/* QCI not supported */
		return snprintf(buf, PAGE_SIZE, "not supported\n");

	return snprintf(buf, PAGE_SIZE,
			"0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
			ap_configuration->adm[0], ap_configuration->adm[1],
			ap_configuration->adm[2], ap_configuration->adm[3],
			ap_configuration->adm[4], ap_configuration->adm[5],
			ap_configuration->adm[6], ap_configuration->adm[7]);
}

static BUS_ATTR(ap_control_domain_mask, 0444,
		ap_control_domain_mask_show, NULL);

static ssize_t ap_usage_domain_mask_show(struct bus_type *bus, char *buf)
{
	if (!ap_configuration)	/* QCI not supported */
		return snprintf(buf, PAGE_SIZE, "not supported\n");

	return snprintf(buf, PAGE_SIZE,
			"0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
			ap_configuration->aqm[0], ap_configuration->aqm[1],
			ap_configuration->aqm[2], ap_configuration->aqm[3],
			ap_configuration->aqm[4], ap_configuration->aqm[5],
			ap_configuration->aqm[6], ap_configuration->aqm[7]);
}

static BUS_ATTR(ap_usage_domain_mask, 0444,
		ap_usage_domain_mask_show, NULL);

static ssize_t ap_config_time_show(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%d\n", ap_config_time);
}

static ssize_t ap_interrupts_show(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%d\n",
			ap_using_interrupts() ? 1 : 0);
}

static BUS_ATTR(ap_interrupts, 0444, ap_interrupts_show, NULL);

static ssize_t ap_config_time_store(struct bus_type *bus,
				    const char *buf, size_t count)
{
	int time;

	if (sscanf(buf, "%d\n", &time) != 1 || time < 5 || time > 120)
		return -EINVAL;
	ap_config_time = time;
	mod_timer(&ap_config_timer, jiffies + ap_config_time * HZ);
	return count;
}

static BUS_ATTR(config_time, 0644, ap_config_time_show, ap_config_time_store);

static ssize_t ap_poll_thread_show(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%d\n", ap_poll_kthread ? 1 : 0);
}

static ssize_t ap_poll_thread_store(struct bus_type *bus,
				    const char *buf, size_t count)
{
	int flag, rc;

	if (sscanf(buf, "%d\n", &flag) != 1)
		return -EINVAL;
	if (flag) {
		rc = ap_poll_thread_start();
		if (rc)
			count = rc;
	} else
		ap_poll_thread_stop();
	return count;
}

static BUS_ATTR(poll_thread, 0644, ap_poll_thread_show, ap_poll_thread_store);

static ssize_t poll_timeout_show(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%llu\n", poll_timeout);
}

static ssize_t poll_timeout_store(struct bus_type *bus, const char *buf,
				  size_t count)
{
	unsigned long long time;
	ktime_t hr_time;

	/* 120 seconds = maximum poll interval */
	if (sscanf(buf, "%llu\n", &time) != 1 || time < 1 ||
	    time > 120000000000ULL)
		return -EINVAL;
	poll_timeout = time;
	hr_time = poll_timeout;

	spin_lock_bh(&ap_poll_timer_lock);
	hrtimer_cancel(&ap_poll_timer);
	hrtimer_set_expires(&ap_poll_timer, hr_time);
	hrtimer_start_expires(&ap_poll_timer, HRTIMER_MODE_ABS);
	spin_unlock_bh(&ap_poll_timer_lock);

	return count;
}

static BUS_ATTR(poll_timeout, 0644, poll_timeout_show, poll_timeout_store);

static ssize_t ap_max_domain_id_show(struct bus_type *bus, char *buf)
{
	int max_domain_id;

	if (ap_configuration)
		max_domain_id = ap_max_domain_id ? : -1;
	else
		max_domain_id = 15;
	return snprintf(buf, PAGE_SIZE, "%d\n", max_domain_id);
}

static BUS_ATTR(ap_max_domain_id, 0444, ap_max_domain_id_show, NULL);

static struct bus_attribute *const ap_bus_attrs[] = {
	&bus_attr_ap_domain,
	&bus_attr_ap_control_domain_mask,
	&bus_attr_ap_usage_domain_mask,
	&bus_attr_config_time,
	&bus_attr_poll_thread,
	&bus_attr_ap_interrupts,
	&bus_attr_poll_timeout,
	&bus_attr_ap_max_domain_id,
	NULL,
};

/**
 * ap_select_domain(): Select an AP domain.
 *
 * Pick one of the 16 AP domains.
 */
static int ap_select_domain(void)
{
	int count, max_count, best_domain;
	struct ap_queue_status status;
	int i, j;

	/*
	 * We want to use a single domain. Either the one specified with
	 * the "domain=" parameter or the domain with the maximum number
	 * of devices.
	 */
	spin_lock_bh(&ap_domain_lock);
	if (ap_domain_index >= 0) {
		/* Domain has already been selected. */
		spin_unlock_bh(&ap_domain_lock);
		return 0;
	}
	best_domain = -1;
	max_count = 0;
	for (i = 0; i < AP_DOMAINS; i++) {
		if (!ap_test_config_domain(i))
			continue;
		count = 0;
		for (j = 0; j < AP_DEVICES; j++) {
			if (!ap_test_config_card_id(j))
				continue;
			status = ap_test_queue(AP_MKQID(j, i), NULL);
			if (status.response_code != AP_RESPONSE_NORMAL)
				continue;
			count++;
		}
		if (count > max_count) {
			max_count = count;
			best_domain = i;
		}
	}
	if (best_domain >= 0){
		ap_domain_index = best_domain;
		spin_unlock_bh(&ap_domain_lock);
		return 0;
	}
	spin_unlock_bh(&ap_domain_lock);
	return -ENODEV;
}

/*
 * helper function to be used with bus_find_dev
 * matches for the card device with the given id
 */
static int __match_card_device_with_id(struct device *dev, void *data)
{
	return is_card_dev(dev) && to_ap_card(dev)->id == (int)(long) data;
}

/* helper function to be used with bus_find_dev
 * matches for the queue device with a given qid
 */
static int __match_queue_device_with_qid(struct device *dev, void *data)
{
	return is_queue_dev(dev) && to_ap_queue(dev)->qid == (int)(long) data;
}

/**
 * ap_scan_bus(): Scan the AP bus for new devices
 * Runs periodically, workqueue timer (ap_config_time)
 */
static void ap_scan_bus(struct work_struct *unused)
{
	struct ap_queue *aq;
	struct ap_card *ac;
	struct device *dev;
	ap_qid_t qid;
	int depth = 0, type = 0;
	unsigned int functions = 0;
	int rc, id, dom, borked, domains;

	AP_DBF(DBF_DEBUG, "ap_scan_bus running\n");

	ap_query_configuration();
	if (ap_select_domain() != 0)
		goto out;

	for (id = 0; id < AP_DEVICES; id++) {
		/* check if device is registered */
		dev = bus_find_device(&ap_bus_type, NULL,
				      (void *)(long) id,
				      __match_card_device_with_id);
		ac = dev ? to_ap_card(dev) : NULL;
		if (!ap_test_config_card_id(id)) {
			if (dev) {
				/* Card device has been removed from
				 * configuration, remove the belonging
				 * queue devices.
				 */
				bus_for_each_dev(&ap_bus_type, NULL,
					(void *)(long) id,
					__ap_queue_devices_with_id_unregister);
				/* now remove the card device */
				device_unregister(dev);
				put_device(dev);
			}
			continue;
		}
		/* According to the configuration there should be a card
		 * device, so check if there is at least one valid queue
		 * and maybe create queue devices and the card device.
		 */
		domains = 0;
		for (dom = 0; dom < AP_DOMAINS; dom++) {
			qid = AP_MKQID(id, dom);
			dev = bus_find_device(&ap_bus_type, NULL,
					      (void *)(long) qid,
					      __match_queue_device_with_qid);
			aq = dev ? to_ap_queue(dev) : NULL;
			if (!ap_test_config_domain(dom)) {
				if (dev) {
					/* Queue device exists but has been
					 * removed from configuration.
					 */
					device_unregister(dev);
					put_device(dev);
				}
				continue;
			}
			rc = ap_query_queue(qid, &depth, &type, &functions);
			if (dev) {
				spin_lock_bh(&aq->lock);
				if (rc == -ENODEV ||
				    /* adapter reconfiguration */
				    (ac && ac->functions != functions))
					aq->state = AP_STATE_BORKED;
				borked = aq->state == AP_STATE_BORKED;
				spin_unlock_bh(&aq->lock);
				if (borked)	/* Remove broken device */
					device_unregister(dev);
				put_device(dev);
				if (!borked) {
					domains++;
					continue;
				}
			}
			if (rc)
				continue;
			/* new queue device needed */
			if (!ac) {
				/* but first create the card device */
				ac = ap_card_create(id, depth,
						    type, functions);
				if (!ac)
					continue;
				ac->ap_dev.device.bus = &ap_bus_type;
				ac->ap_dev.device.parent = ap_root_device;
				dev_set_name(&ac->ap_dev.device,
					     "card%02x", id);
				/* Register card with AP bus */
				rc = device_register(&ac->ap_dev.device);
				if (rc) {
					put_device(&ac->ap_dev.device);
					ac = NULL;
					break;
				}
				/* get it and thus adjust reference counter */
				get_device(&ac->ap_dev.device);
				/* Add card device to card list */
				spin_lock_bh(&ap_list_lock);
				list_add(&ac->list, &ap_card_list);
				spin_unlock_bh(&ap_list_lock);
			}
			/* now create the new queue device */
			aq = ap_queue_create(qid, type);
			if (!aq)
				continue;
			aq->card = ac;
			aq->ap_dev.device.bus = &ap_bus_type;
			aq->ap_dev.device.parent = &ac->ap_dev.device;
			dev_set_name(&aq->ap_dev.device,
				     "%02x.%04x", id, dom);
			/* Add queue device to card queue list */
			spin_lock_bh(&ap_list_lock);
			list_add(&aq->list, &ac->queues);
			spin_unlock_bh(&ap_list_lock);
			/* Start with a device reset */
			spin_lock_bh(&aq->lock);
			ap_wait(ap_sm_event(aq, AP_EVENT_POLL));
			spin_unlock_bh(&aq->lock);
			/* Register device */
			rc = device_register(&aq->ap_dev.device);
			if (rc) {
				spin_lock_bh(&ap_list_lock);
				list_del_init(&aq->list);
				spin_unlock_bh(&ap_list_lock);
				put_device(&aq->ap_dev.device);
				continue;
			}
			domains++;
		} /* end domain loop */
		if (ac) {
			/* remove card dev if there are no queue devices */
			if (!domains)
				device_unregister(&ac->ap_dev.device);
			put_device(&ac->ap_dev.device);
		}
	} /* end device loop */
out:
	mod_timer(&ap_config_timer, jiffies + ap_config_time * HZ);
}

static void ap_config_timeout(unsigned long ptr)
{
	if (ap_suspend_flag)
		return;
	queue_work(system_long_wq, &ap_scan_work);
}

static void ap_reset_all(void)
{
	int i, j;

	for (i = 0; i < AP_DOMAINS; i++) {
		if (!ap_test_config_domain(i))
			continue;
		for (j = 0; j < AP_DEVICES; j++) {
			if (!ap_test_config_card_id(j))
				continue;
			ap_rapq(AP_MKQID(j, i));
		}
	}
}

static struct reset_call ap_reset_call = {
	.fn = ap_reset_all,
};

int __init ap_debug_init(void)
{
	ap_dbf_info = debug_register("ap", 1, 1,
				     DBF_MAX_SPRINTF_ARGS * sizeof(long));
	debug_register_view(ap_dbf_info, &debug_sprintf_view);
	debug_set_level(ap_dbf_info, DBF_ERR);

	return 0;
}

void ap_debug_exit(void)
{
	debug_unregister(ap_dbf_info);
}

/**
 * ap_module_init(): The module initialization code.
 *
 * Initializes the module.
 */
int __init ap_module_init(void)
{
	int max_domain_id;
	int rc, i;

	rc = ap_debug_init();
	if (rc)
		return rc;

	if (ap_instructions_available() != 0) {
		pr_warn("The hardware system does not support AP instructions\n");
		return -ENODEV;
	}

	/* Get AP configuration data if available */
	ap_init_configuration();

	if (ap_configuration)
		max_domain_id = ap_max_domain_id ? : (AP_DOMAINS - 1);
	else
		max_domain_id = 15;
	if (ap_domain_index < -1 || ap_domain_index > max_domain_id) {
		pr_warn("%d is not a valid cryptographic domain\n",
			ap_domain_index);
		rc = -EINVAL;
		goto out_free;
	}
	/* In resume callback we need to know if the user had set the domain.
	 * If so, we can not just reset it.
	 */
	if (ap_domain_index >= 0)
		user_set_domain = 1;

	if (ap_interrupts_available()) {
		rc = register_adapter_interrupt(&ap_airq);
		ap_airq_flag = (rc == 0);
	}

	register_reset_call(&ap_reset_call);

	/* Create /sys/bus/ap. */
	rc = bus_register(&ap_bus_type);
	if (rc)
		goto out;
	for (i = 0; ap_bus_attrs[i]; i++) {
		rc = bus_create_file(&ap_bus_type, ap_bus_attrs[i]);
		if (rc)
			goto out_bus;
	}

	/* Create /sys/devices/ap. */
	ap_root_device = root_device_register("ap");
	rc = PTR_RET(ap_root_device);
	if (rc)
		goto out_bus;

	/* Setup the AP bus rescan timer. */
	setup_timer(&ap_config_timer, ap_config_timeout, 0);

	/*
	 * Setup the high resultion poll timer.
	 * If we are running under z/VM adjust polling to z/VM polling rate.
	 */
	if (MACHINE_IS_VM)
		poll_timeout = 1500000;
	spin_lock_init(&ap_poll_timer_lock);
	hrtimer_init(&ap_poll_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
	ap_poll_timer.function = ap_poll_timeout;

	/* Start the low priority AP bus poll thread. */
	if (ap_thread_flag) {
		rc = ap_poll_thread_start();
		if (rc)
			goto out_work;
	}

	rc = register_pm_notifier(&ap_power_notifier);
	if (rc)
		goto out_pm;

	queue_work(system_long_wq, &ap_scan_work);
	initialised = true;

	return 0;

out_pm:
	ap_poll_thread_stop();
out_work:
	hrtimer_cancel(&ap_poll_timer);
	root_device_unregister(ap_root_device);
out_bus:
	while (i--)
		bus_remove_file(&ap_bus_type, ap_bus_attrs[i]);
	bus_unregister(&ap_bus_type);
out:
	unregister_reset_call(&ap_reset_call);
	if (ap_using_interrupts())
		unregister_adapter_interrupt(&ap_airq);
out_free:
	kfree(ap_configuration);
	return rc;
}
device_initcall(ap_module_init);